Looking for portable oscilloscope

[abgx1]

But was your ground completely disconnected?

I think there is some confusion and everybody is testing something else. I will try to draw a schematics...

[2N3055]

Do any of fluke's handheld oscilloscopes have a separate ground?!
Even the Fluke 190 Series III ScopeMeter doesn't include it, that is, I can't see it anywhere, even though it's a +4000 Euro instrument.
As written above, compliance with the safety regulations is the most important.

Fluke has scope with galvanically fully isolated channels from scope ground and each other.
Keysight has has scope with galvanically fully isolated channels from scope ground and each other.
R&S has has scope with galvanically fully isolated channels from scope ground and each other.
Siglent has has scope with galvanically fully isolated channels from scope ground and each other. That is most affordable one.

Those are I know of. There could be more..

[mikeselectricstuff]

The Micsig tablets scopes are also well worth a look.

[nctnico]

The Micsig tablets scopes are also well worth a look.

I agree. And they are rugged as well. Recently I dropped mine and it survived that just fine. For measuring high voltages / mains safely, you'd need a CAT rated differential probe though.

[2N3055]

The Micsig tablets scopes are also well worth a look.

They used to have an isolated handhelds before but not anymore.

[abgx1]

What is the cheapes differential probe which can be used on main voltage?

[nctnico]

What is the cheapes differential probe which can be used on main voltage?

Last time I checked the CAT rated ones from Micsig are the most economic ones.

[shapirus]

I believe there also were some feasible DIY designs discussed on this forum (that someone actually implemented). Search should show them.

[Fungus]

What is the cheapes differential probe which can be used on main voltage?

Micsig.

[alm]

So it doesn't work. I have just verified this with a handheld battery-powered scope: when the ground clips are detached, the Ch1-Ch2 (math) waveform becomes garbage.

The signals need to stay within range for both channels. Especially with a floating scope the reference level may well be at a level away from ground, pulling the signals relative to the reference out of range. With a grounded scope this is not going happen because CH1 and CH2 are always referenced to ground. This is also a potential problem with real differential probes. Which is for example why Fluke tells you to ground the floating scope when using two differential probes at the same time.

For measuring high voltages / mains safely, you'd need a CAT rated differential probe though.

No, you don't need a differential probe. A single-ended probe designed for floating measurements will also work. It's not like the reference level is moving much relative to earth. If you read the manual for high voltage differential probes, they have statements like "make sure the oscilloscope is grounded" or "These probes are designed for use with oscilloscopes that have a common terminal at GROUND POTENTIAL". So I'd say a single-ended probe for floating measurements is a better choice for a battery-powered scope with isolated inputs (the only type of battery-powered scope I'd use on mains). Either that, or use a grounded scope with a high voltage differential scope.

[nctnico]

For measuring high voltages / mains safely, you'd need a CAT rated differential probe though.

No, you don't need a differential probe. A single-ended probe designed for floating measurements will also work. It's not like the reference level is moving much relative to earth. If you read the manual for high voltage differential probes, they have statements like "make sure the oscilloscope is grounded" or "These probes are designed for use with oscilloscopes that have a common terminal at GROUND POTENTIAL". So I'd say a single-ended probe for floating measurements is a better choice for a battery-powered scope with isolated inputs (the only type of battery-powered scope I'd use on mains). Either that, or use a grounded scope with a high voltage differential scope.

You are confusing a few things here.

1) There is no such thing as a single ended probe for floating measurements. You always need to clip the reference / ground side of a probe somewhere in order to measure a voltage difference between two points.
2) An oscilloscope with isolated inputs is functionally comparable to using a differential probe + normal oscilloscope. Only difference is that the isolation happens inside or outside the oscilloscope
3) Needing grounding is a safety issue. If the differential probe breaks or (more likely) the user makes an error, a non-isolated oscilloscope which is floated can present dangerous voltages to the user.

So in the end the choice is between paying more for an oscilloscope with floating inputs compared to using an external isolation device like a differential probe combined with an oscilloscope. What is most economic and desirable, depends on the requirements. Handheld oscilloscopes with isolated inputs typically have less features as they are more geared towards simple field measurements.

[alm]

1) There is no such thing as a single ended probe for floating measurements. You always need to clip the reference / ground side of a probe somewhere in order to measure a voltage difference between two points.

Clipping the reference lead somewhere doesn't make the measurement any less floating, as long as the reference lead is isolated from earth. A single-ended probe is a single-ended probe (so with a signal and reference lead with an imbalanced impedance to ground) that is specifically designed for floating measurements like the HCK/Staubli IsoProbe series has an isolated BNC connector and a reference lead that is much better insulated than your average probe designed for grounded scopes.

3) Needing grounding is a safety issue. If the differential probe breaks or (more likely) the user makes an error, a non-isolated oscilloscope which is floated can present dangerous voltages to the user.

Needing ground is a safety issue for scopes with non-isolated inputs. So there is a distinct advantage here for scopes with isolated inputs in places where grounding is difficult.

I do agree that scopes with isolated inputs are more expensive and more limited in features. I wouldn't want one as my primary bench scope, but it sounded like this application doesn't need a particularly advanced scope.

[rhb]

I have an HDS272S which I'd ordinarily recommend, however as you mention 3 phase, a Hanmatek DOS1104 *might* be  what you want.  Internally it's an Owon SDS 1104 but without the deep memory chip or the mains supply.  I runs on 5 V in.  I ordered one from Aliexpress along with a couple of 10 A-hr LiPo cells.  The BMS/boost convertors came today.

With appropriate probes, the scope can float from ground and be used safely with appropriate practices.  The DOS 1104 is $206 USD.  If things go to plan I'll have a quite decent portable scope without the handheld version limitations for about $230.

I currently have a DOS 1102 and am quite impressed.  In particular, it has a good FFT which is very responsive.

I'll be starting a thread on HW hacking the Hanmateks to run on internal battery.

Have Fun!
Reg

[abgx1]

Thank you, everybody, and sorry that I did not respond for 3 days; I had a busy week. But as I am reading your posts, I feel like it is just a bad idea to frequently measure mains voltage without differential probes + proper ground.


1. I have abandoned the idea of a handheld oscilloscope. It doesn't look safe to measure main voltage with them even with differential probes.
2. I have decided to buy Micsig differential probes.

Owon doesn't have proper grounding, so it is out of the game.
Hanmatek is not available in the EU, I need to buy it on a company VAT number. So it has to be a shop located in the EU.

So actually my shopping cart looks like this:
https://eleshop.eu/rigol-dho804-oscilloscope.html
https://eleshop.eu/dp10013-differential-probe-100-mhz-1300v.html


Any advice before making final order?

[csuhi17]

https://www.banggood.com/hu/Micsig-Oscilloscope-1300V-100MHz-High-Voltage-Differential-Probe-Kit-3_5ns-Rise-Time-50X-or-500X-Attenuation-Rate-DP10013-p-1987592.html?cur_warehouse=CN&rmmds=search

you won't get it this year, but I think it's much cheaper.

[abgx1]

I cannot order outside of EU... I have ordered everything from local shop... 399 for the scope and 189€ for micsig probes

Sadly, rigol is out of stock everywhere, so have to wait atleast till mid january. I will let you know then

[csuhi17]

I cannot order outside of EU... I have ordered everything from local shop... 399 for the scope and 189€ for micsig probes

Sadly, rigol is out of stock everywhere, so have to wait atleast till mid january. I will let you know then

https://www.batterfly.com/shop/en/rigol-dho804?search=Dho804&description=true

[aae30]

I'll be starting a thread on HW hacking the Hanmateks to run on internal battery.

Did you ever get around to doing this? Took a look inside, and looks to me like it might be
relatively simple to do w/o (m)any custom parts.

[GigaJoe]

OWON HDS160
I did advise it to friend  who work for solar panels \ inverters on a field for some basic troubleshooting.   From his word: It appears extremely useful to use the same probe for scope and voltage metering , switching back and forward  scope to DMM by single button. ...  you basically holding same point and switching .. Scope are OK up to 200 -300K freq , exact max for inverters. it has 1:500V Div. for scope  He had a case it swallow 1200 V P-P  .

if you forgot to recharge - just replace one 18650
on negative side a bit small screen for scope , and some homemade shade screen to off direct light .  it quite light to carry .   so after a few month all his crew got the same

before i gave him my OWON HDS241
the response was ..  to much cables to deal it on roof,  sometime it get lost ... a bit expensive to replace if it fall from roof accidently .. so that HDS160 ( 120 - 20000 counts) almost ideal
and 60000 - nice wide range ...  switch to 600 still have 0.1 resolution

[norbert.kiszka]

Rigol DHO800 and DHO900 series are powered from USB-C PSU or power bank. But there is one thing that most of the electronic/electrical engineers/technicians will like to not think of or just forget to think of.

There is something called as a earthing systems, which IMHO is not a fully proper name, because also applies to simplest devices powered from a single 1.5 V battery and fully enclosed. This is a just a surface of a safety knowledge of a safety in electrical devices. I think, most of people here, didn't spend hours on state exams about safety related to any electrical work.

Extra low voltage (ELV) PSU's like USB ones, creates another earthing system. Which is one of three: SELV, PELV and FELV. USB power supplies usually are SELV, at least in theory. In practice those are often between SELV and FELV, which means this is a huge safety hazard, especially if there is a tiny amount of moisture in the air. 70% air humidity can be a death trap - I know something about it from my personal experience.

Working with the oscilloscope and power grid it's not just simple as just buy first better probe or make it by Yourself. When scope is powered from a power supply that claims to be SELV, You either need to have fully secured PE-GND connection or to be absolutely sure about Your equipment and what are You doing. Bananas plugs with thin and Chinese made "copper", are very far from that.

Rigol supplied many of those scopes with a PSU's which are death traps. I bought DHO924S which was supplied with a Lite-On USB-C PSU. I tested it with a insulation tester (fancy ohm meter with higher voltage) and it failed pretty quickly. After I tear it down, reason was pretty obvious - it was designed to be very cheap, without safety in mind.

I heard in last couple month Rigol switched those two previous PSUs to a Delta brand. From my experience Delta makes very reliable and very safe power supplies and other things. But You never know if this is a genuine one or some fake.

Used insulation testers (another name: Riso meter) are very cheap. You can get one for like 80$, which can save Your or somebody else life. Not speaking of health, because burns and paralysis are not fun.